The \(\log g \times T_{eff}\)  diagram of the sample stars is shown in Fig. 2 with the colour coded for metallicity [Fe/H]. PARSEC mass tracks for different metal abundances are used to determine the luminosity classes of the sample stars [1]}, [2]}, [3]}. The evolutionary tracks generated for different heavy element abundances (\(Z\)  = 0.040, 0.030, 0.020, 0.017, 0.014, 0.010, 0.008, 0.006, 0.004 and 0.002) are converted to [Fe/H] metallicities using the formulae given by Jo Bovyhttps://github.com/jobovy/isodist/blob/master/isodist/
Isochrone.py
 [4]}, [5]}, [6]}, [7]}. Then, zero age main sequence (ZAMS) and terminal age main sequence (TAMS) evolutionary tracks corresponding to the metal abundance ranges for mean \(Z\)  values were established (Fig. 3). The luminosity classes of the sample stars were determined by the metallicity intervals as indicated in Fig. 3 and marked on the \(\log g \times T_{eff}\)  diagrams. Stars between the ZAMS and TAMS curves are classified as main-sequence stars, while the ones above the TAMS curve are adopted as evolved stars, i.e. those with \(\log g\ge 3.5\)  as sub-giants and the ones with \(\log g<3.5\)  as giants. Thus, the number of stars with different luminosity classes turned out to be as follows: 245 main-sequence, 187 sub-giants, and 124 giants.
